Co-occurrence of vertebral artery hypoplasia and high jugular bulb in patients undergoing cranial magnetic resonance imaging.

We aimed to assess the frequency and coexistence of vertebral artery hypoplasia (VAH) and high jugular bulb (HJB) in subjects who underwent cranial magnetic resonance imaging (MRI) for diverse indications. This was a retrospective study in which 2184 consecutive patients who underwent cranial MRI were screened. Age, sex, and reasons for ordering cranial MRI were obtained from hospital database. Nineteen patients were excluded from the study. We defined VAH as a vertebral artery whose diameter was smaller than 2 mm with an asymmetry ratio of ≤ 1:1.7. HJB was defined as the jugular bulb lying higher than the inferior portion of the internal acoustic meatus. Pearson's χ test was used to study the association between VAH and HJB. A total of 2165 subjects were included in the final analysis. Median age was 34 years (min-max 1-98 years). Females constituted 51.4%. The most common complaint for which brain MRI was ordered was headache (68.5%), followed by vertigo (13%). VAH was present in 890 subjects (40.9%). The majority of the patients had unilateral VAH, mainly on the right side (72.9%). HJB was present in 1067 subjects (48.9%) and 24.9% of the temporal bones. HJB was three times more common on the right side than on the left (71.6%). Five-hundred and seventy-three (26.5%) had VAH and HJB concurrently. When a patient had either VAH or HJV, the likelihood of patient having the other condition was significant (p < 0.001). Binary logistic regression analysis showed that presence of VAH increased the probability of occurrence of HJB threefold and vice versa (p < 0.001, CI 2.502-3.574). This was the first report of significantly common co-occurrence of VAH and HJB.